<!DOCTYPE html>
<html>

<head>
    <meta charset="utf-8">
    <title>页面标题</title>
    <style type="text/css">
        #father1 div {
            color: red;
        }

        #father2 span {
            color: blue;
        }
    </style>
</head>

<body>
    <div id="father1">
        <div>绿叶学习网</div>
        <div>绿叶学习网</div>
    </div>
    <div id="father2">
        <p>绿叶学习网</p >
        <p>绿叶学习网</p >
        <span>绿叶学习网</span>
    </div>
</body>

</html>